Photographic color process



Patented June 3', 1941 v 2,244,589 rnoroonarnro oononrnoonss Louis Yanket, Long Island City, N. v.

No Drawing. Application October 31, 1938,

Serial No. 238,077 r 2 Claims.

This invention relates to photographic color processes and more particularly to color image development processes.

An important object of the invention is to provide a novel process for obtaining the color images by means of color image developers.

Another important object is to provide such a process wherein a single-layer, photographicsensitive silver halides emulsion upon a, suitable base is exposed under a color-separation negative and the latent image developed into a first color image, simultaneously with the formation of a metallic silver image, which latter is re-converted into photographic sensitive silver halides; and these are exposed under a second color-separation negative and the latent image developed into a second color image, simultaneously with the re-formation of certain portions of the metallic silver image, which latter is re-converted into photographic-sensitive silver halides, and these are exposed under a third color-separation negative and the latent image developed into a third color image, simultaneously with the re-formation of certain metallic silver which latter is re-converted into silver halides and suitably removed,

Other objects of the invention will be apparent during the course of the following detailed description of the process.

Suitable photographic negatives are produced by any suitable conventional process, such as a red record negative. a blue record negative and a yellow record negative, .The negatives are printed by means of light passing thru them from a source of light within the said photographic printer in the following manner:

A single-layer, photographic-sensitive silver halides emulsion upon a suitable base is exposed under the red record negative and developed into a magenta colored image, this magenta colored image has in contact with itla metallic silver image, this silver image is converted into photographic sensitive silver halides and the sheet of paper is re-exposed under the blue record negative and developed into a blue colored image, this blue colored image has in contact with it a metallic silver image, this silver image is converted into photographic sensitive silver halides and the paper is re-exposed under the yellow record negative and developed into a yellow colored image, this yellow colored image has in contact with it a metallic silver image, this silver image is converted into silver halides, these silver halides are removed with a solution of sodium thiosulphate, or other solvent of silver halides, and the natural color photograph washed in water and dried. The finished photograph is free of silver, the three super-imposed images are not silver images but images in the nature of dye images, and all silver, or silver halides, were removed by the solution of sodium thlosulphate, or other solvent of silver, and/or silver halides.

It is now apparent from the foregoing (and has been found wholly satisfactory). that this same process may be employed in so-called optical printing.

The following are detailed steps in the novel contact printing:

The negative for the magenta image is placed upon a suitable printer, the photographic sensitive emulsion upon a suitable base (hereinafter termed photographic sensitive paper for convenience) is then placed upon this negative, and the negative is printed in the conventional manner used in photography. The exposed photographic sensitive paper is then placed in the following magenta image developer, made up substantially as follows:

the following solution is then added: Potassium bromide solution 10%....cc.- 1 to 1.5 the image is developed in about 45 seconds. The

magenta, image consists of two images in contact with each other, i. e.: the magenta image and a I metallic silver image, the metallic'silver image must be converted back into the original photographic sensitive silver halides and made an integralpar't of the photographic sensitive silver halides in the emulsion, which had not been acted upon by the exposure light and the color image developer, the emulsion thus presenting a homologous layer of photographic sensitive silver halides to the negative for the blueimage which is the next negative to be Printed.

The metallic silver image is converted back into the photographic sensitive silver halides by means of the following solution: (the photographic sensitive paper being rinsed in water before being placed in the solution) Water on 1000 Potassium bromide grams 20 Sodium. chloride do .25 Potassium ferricyanide do 15 Sodium carbonate do 15 The ratio of chlorine to-bromine in-the above solution may vary as follows: .chlorine 100: bromine 10 to chlorine 100; bromine 350. The ratio to be used depends upon the original contrast of the original silver halides, the ratio thus selected form silver halides capable of giving the same contrast as the original silver halides.

The higher the bromine ratio the softer the contrast. Other bromides and chlorides may be used in place of the above compounds and the ratio of chlorine to bromine sustained by using chlorine equivalent or bromine equivalent of the substituted chloride or bromide.

The photographic sensitive paper bearing the magenta image is now washed in water for a few minutes. 7

The negative for the magenta image is taken oh the printer and the negative for the blue image. is placed upon the printer; the photographic sensitive paper bearing the magenta image is now placed upon the negative and the negative printed in the same manner as the negative for the magenta image had been printed. The exposed photographic sensitive paper is now placed in the following blue image develop-er made up substantially as follows: Water i r 1000 Sodium carbonatem grams 12.500 v Sodium sulphite ;do 7

Sodium hydroxide do 0.800 Sodium sulphate. ..do 100 Diethyl-p-phenylenediamine hydrochlo-- ride grams 1.800

the following 'solut ionis then added: 2,4-dichloro-1 naphthol gram 0.800 Methyl alcohol cc 50 the following solution is then added:

Potassium bromide solution cc 2 to 2.5

the image is developed in about 45seconds.

The blue image consists of two images in contact with each other, i. e.: the blue'image and a metallic silver image, the metallic silver image must be converted back into the original photoasse ses magenta and blue images is now washed in water for a few minutes.

The negative for the blue image is taken 011 the printer and the negative for the yellow image is placed upon the printer; the photographic sensitive paper bearing. the magenta and blue images is now placed upon the negative and the negative printed in the same manner as the negative for the blue image had been printed. The exposed photographic sensitive paper is now placed in the following yellow image developer and the yellow image developed:

the image is developed in about 45 seconds.

, Ifhe yellow image consists of two images in back into silver halides by means of the followcontact with each other, 1. e the yellow image and"a metallic silver ima e,-- the metallic silver image is not needed in t e color photograph, therefore. the metallic silver image is converted "ing solution: (the photographic sensitive paper being rinsed in water before being placed in the sdlution) Water cc 1000 Potassium bromide" grams. 20

Sodium chloride do Potassium ferrlcyanide do 15 Sodium carbonate do the photographic sensitive paper bearing the graphic sensitive silver halides and made an integral' partfof the photographic sensitive silver halides in the emulsion which had not been acted 'upon by the exposure light and the color image developer, the emulsion thus presenting a homologous layer of photographic sensitive silver.

halides to the negative for the yellow image which is the next negative to be printed.

The metallic silver image is converted back into the photographic sensitive silver halides by means of the following:' solution: (the photographic sensitive paper being rinsed in water before being placed in the solution) v 1000 Water V cc Potassium bromide "grams--. 20 Sodium chloridedo..r 25 a Potassium' ferricyanide do 15 Sodium carbonate; do 15 the photographic sensitive paper bearing the.

' magenta, the blue, and the yellow images, is now washed in water for a few minutes; and fixed in the following hypo fixing bath:

Sodium thiosulphate grams 200 Sodium, carbonate do 5 Water nl000 The hypo bath removes the silver halides which were formed in the above solution, and also any silver halides which had not been acted upon by the exposure light and the color image developers; the emulsion of the color photograph no longer contains any silver, either as metallic silver or as silver halides; the three superimposed images are not silver images such as would be present in a black and white photograph, but images in the nature of dye images. The color photograph is now washed in water, and the color photograph is then dried.

From the foregoing it can be now seen that a 'novel color image developing process has been disclosed, employing a single-layer photographicsensitive silver halides emulsion, with the metallic silver image being re-converted each time into a photographic sensitive silver halides emulsion,

and so-called chemical toning, like are obviated. I

I claim: v

1. Those steps in a photographic color process Which pr e e pos g an emulsion layer of mixed silver bromide and silver chloride, developing and coloring the developed image upon tanning and the said layer, and treating said layer to a resensitizing bath containing soluble chloride and soluble bromide in ratio to give the resensitized portions of said layer substantially the same contrast characteristics as in the original emulsion.

2. Those steps in a photographic color process which comprise exposing, by means of a color separation negative, an emulsion layer of mixed silver bromide and silver chloride, developing the latent image by means of a color developer. and treating the developed image to a resensitizing bathcontaining soluble chloride and soluble bromide in ratio to give the resensitized portions of said emulsion layer substantially the same contrast characteristics as in the original emulsion.

LOUIS YANKET. 

